Click on the Object select icon (marked with red in the illustration below). In the
popup window choose: Sizing applies Time Stretch.
Click in the sound clips right bottom corner and drag the file to the length desired
(in my case I double the sound files length), look at the animation below).
As default Cubase tries to do this as fast as possible. This may result in a time
stretch that has some unwanted artifacts. To make a much smother time stretch you
can change the time stretch algorithm.
To change the time stretch algorithm choose File>Preference, look at the illustration
In the preference window chose Editing>Audio.
In the algorithm menu chose MPEX. In the submenu chose a Quality and make setting
that seems logic to you. Solo musical handles complex monophonic sound and the poly
settings is best suited for complex polyphonic sounds (like a whole mix). Having
said that, you have to try this out yourself, some of these settings produce unexpected
(and sometimes nice) results especially if you make long time stretches.
When you made your quality setting, click on Apply or OK to make it active, look
at the illustration below. Go back to your sound file and try it out.
And, DON’T FORGET THE UNDO possibility, if you don’t like the result just do a ctrl-Z
and the time stretch (last thing you did) become undone.